DAVID-Laserscanner Forum

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before a view days I started the David software on a 32bit PC. I was quite happy to see that on this PC the merging/alignment process of two single scans (of a size of nearly 40 - 60 MB) was done within 5 to 10 seconds. As I never did postprocess my scans on a desktop PC (I did it only on my laptop) before, I tried to run the software also on my PC (also 32bit Windows version). But this time - as on my laptop - it needed nearly 2 minutes to merge two scans. Thus, I'd like to know how I can adapt the hardware of my PC (eg. additional main memory, better graphics board, etc.) to make merging within a few seconds possible. Any recommendations?

On WIN32 a single app can only use up to 4GB RAM (against WIN 64 where the OS handles more RAM). Some basic RAM amount is used by the OS and some background apps. You may look into your TaskManager to see if 4GB RAM are still available after subtracting this basic load.You may consider to update WIN to a 64 bit version (and maybe add some further RAM) which also allows a better handling of multiple CPU cores.Without upgrading your system:The time DAVID needs to align a partial scan to a target depends a lot on the target. If this target is a group of scans, alignment time will rise with the number of grouped scans. So try to keep the number of partial scans in a group as low as possible. E.g. in most cases there's no need to group aligned scans if you are doing a single 360° alignment. Let's say you've done 8 scans to get 360° (scan 1 to scan 8 ). To align scan 1 to 7 you should not need any grouping. Only scan 8, which fills the final gab between scan 1 and 7 needs a group of scan 1 and 7 (scan 2 till 6 shouldn't be in that group).If you've done more scans (maybe a second 360° sequence 90° rotated):After aligning the first sequence, you may consider a rough low res fusion (without holes filled) on this and save all aligned scans (1-8) in their new registration.Now load the low res fusion to be a target for scans 9-16 instead of grouping scan1-8.Finally delete this rough target and reload scans1-8 for a final global fine registration and high res fusion.

Thus, the software performance mainly depends on memory and not on graphics board?!

I'll also try your trick with fusion of first 8 scans which will work as target for subsequent scans. Thank you. Unfortunately I think this will only save one or two minutes while an increase in pairwise alignment time may save hours.

Pairwise alignment usually takes only a few seconds, even on slower computers... Are you sure it is always so slow on your computer?I would recommend a modern CPU (2,4 or 8 cores) and lots of RAM (e.g. 8 GB) and 64-bit OS.Sven